PHILADELPHIA (AP) — Fire officials say they have not been able to determine the cause of a December blaze that killed a Philadelphia firefighter.

Fire Commissioner Derrick Sawyer said Tuesday that the Dec. 9 blaze in the city's West Oak Lane neighborhood that killed Lt. Joyce Craig began in the basement recreation room of the two-story row home.

But he said investigators were unable to determine a point of origin or an ignition source "due to the almost complete destruction" of the room. The investigation could be reopened should new information become available.

Thirty-six-year-old Craig, an 11-year veteran, became trapped in the basement of the home where an elderly woman was later rescued. The mother of two was the first female firefighter in the city to die in the line of duty.